Method for producing a variegated surface on fiberboard



Feb. 19, 1946. H. K.'LINZELL METHOD FOR PRODUCING A ,VARIEGATED SURFACE ON FIBER BOARD Filed March 31, 1941 Patented Feb. 19, 1946 variegated surfaces.

product manufactured 2,395,375 f I II METHOD FOR PRODUCING A VARIEGATED summon on FIBEBBOARD Harry K. Linzell, Ingleside, Ill., assignor to United i States Gypsum Company, Chicago, 111., a cor- Yporation of Illinois Application March 31, 1941 SerialNo 336,106?

100mm (01.92-41) II 1 f" am throughout a singlejpiecef. Consequently; ifa paint or lacquer is 'appliedthereon, the more;

This invention relates composition boards and more particularly to fibervboards having Several methods have been proposed in the past for the production of compositionboards such as insulating board and. compressed fiber board known as hardboard. Thesemethods in general comprise the collection of vegetable fiber or other comminuted materialin any suitable manner to form a mat or slab which is subsequently dried and pressed toform the desired product, the characteristicsof the resultantprodnot depending to a great extent upon the ma: terials incorporated within the mat and the'manner in which they arecompounded-a'nd'subse quently pressed. I Products thus produced present in general a more or less uniformly colored and textured surface. It is'desirable in certain cases to produce a product which has a variegated surface and presents a, pleasing appearance. A product of this character is also desir able since the variegated surfacelwill tend o mask certain blemishes thatoften occur in a or prepared by d the usual methods. Y H ;1: f In order to produce a variegated surface on fibrous products, it hasbeen the custom inthe past to apply the coloring matter in the form' of paint or lacquer to the surface after the product has been formed. Attempts to incorporate a dye into the surface of the finished-product have not been entirely satisfactory because of variations in the material treated and variable char acteristics of the particular dye employed.

In the manufacture of hard pressed board it has been particularly difficult .to secure a product which will present a pleasantly appearing varie:

.and the resulting surface of the surface variesjto a considerable porous portions will'absorb the coating material to a greater extent than' the densierportionsf willpresent an uncle-- Sil'fllbl mottled effect.

a It iscQnSequentIy oneiobjectof invention to provide a composition board presenting 'a pIeasing surface effect inwhich'small porosity and havinga'variegated surface;

A further object of this inventionis to provide I a hard, uniformly dense fiber board presenting a pleasing surface effect of -varieg'ated colors.

Further and additional objects of this inveni tion will appear fromtlie followlng" descri.ption and the appended claims.

One Of the rnethods for:produdingftheproduct of this invention 'contemplate'sthemse of a bleeding 'dye which may beincorporated into 3 I 1 the materialtpreliminaxily" to the formation of uble or will readily migratethroughgthe material.

with the liquidthat was containedytherein pre- V liminarily to the removal "of 'said liquid. conse the mator slab. The "bleeding"dyesthatmay befused in thisinvention are those'which are solquently, if the-'mat is'saturated with a solution of the bleeding dye and subsequentlydried, the bleeding .dye will have a'tendency to bedrawn with the liquid to the Surface, of the materialand there become concentrated and dry when; the

liquid evaporates. Theisurface will take on't he color ofthe dye, and only smallamounts of the gated surface. However, pressed board havinga variegated surfacewhas beenprepared as described in James N. Devereux Patent No.- 2,225,585.

The process, for the preparation of pressed board as disclosed in this patent discloses a process of pressing a dry mat whose, surface contains a plurality of ridges and hollows. Consequently, when the mat, is subjected to the final pressing, the thicker portions of the mat are compressed to correspondingly greater density than the thinner portions, and. thecolor and texture of the surface adjacent the denser I portions havean appearance different than adjacent portions that are not sodense- In this manner a hard pressed board product which has a variegated surface may be produced However. pressed board that is' prepared in this manner is objectionable since the density and porosity dye will remain within thecore gofthe. mat or slab.

board to the surface, carryingthe dye with it.

' The'water then evaporates, and the dye is pre- 'cipitated onto orconcentratednearthe surface of the fibrous mat; The resulting product isa fiber board having a substantially uniformly co l- 'ored surfacejone side of whih bears a series of hollows and ridgesx.Theuneven"surface,of this. boardmay then be sanded'or ground down in any desired manner to produce a board of unix "surfacedefects arerenderedunnoticeable f; t

I A further obj' t offthisinventionis to ro-I I I vide a composition boardof uniformderisity and According to one embodiment of this invention; I aif'fibrous matmay be prepared from asusp'em sion of fibers in a dilute" solutionof thedyel "The .fibrous mat during formation may be treated according t the methods described in theabove-' referred-to patent to Devereuxl .The resulting mat is then dried, and duringthe drying process] l the water migrates .fromthe centerof the fiber leaving intact the surfaces of the hollow portions. The'resulting uniformly thick fiber board will thus be variegated, the undyed portions being located in the zones where the ridges were v and the dyed prti0ns being located where the hollows were. If desired, the product may'then be pressed at'hig'h temperatures and pressuresv .In order to form aohard, dense board in accordance with the well-known methods.

perature range of from 350 F. to about 500 F.

Such methform thickness, the grinding being only to such an extent that the ridge portions are removed,

or other desired trees or woody plants. This water-fiber suspens on is introduced into the tank I6 through an inlet device I8, and'suction is applied to the inside of the drum in a manner'well known to the art, So as to form a fiber mat IS on the foraminous support. Any excess water overfiowsfrom tank I6 through an outlet device 20. The fiber mat I9 which is formed is led off the drum I5, over a guide roller-2i andbetween endless belts 22 and 23 of suitable material, such as felt, which are pressed heavily against the two faces of the. mat by pairs of pressurerollers 24 "so as to, squeeze out excess dye solution from at a pressure ranging from mere contact up to 1500-2000 lbs. per square inch.

If desired, a similar product may be produced by spraying or otherwise coatingthe fiber insulationboard disclosed in the Devereux Patent No. 2,225,585 with a'dye or some other type of coloring matterJ After drying the coatedinsulation board may preferably be sanded sufficiently to remove the high lights. and expose the uncoated interiorn It willbe-understood that the freshly coatedboard may also be cleaned as by wiping with a cloth, and the coating removed ,from the highspotswhereas the hollows will retain their-coating, The products produced in and it is not intended to be limited by the illustration except by prior art and the appended claims.

Reference will now be made to the drawing,

. figure 1 is .a transverse sectional view of the wet mat from which the product of this invention is formed; a v Fig. 2 is a similar viewof the drylmatfindicating the manner in which the bleeding dye precipitates on the surface of the mat during drying; i Fig. 3 is a transverse sectional view of the mat shown in Fig. 2after the mat has been sanded or ground along, the line A'- A"of Fig.2; and

Fig. 4 isa sectional elevation of an apparatus suitable. for producing a fibrous mat in accordance with this invention. I

Referring now more particularl to the drawing, Fig. 1 depicts aIse'ctional view of the wet mat. which hason onesidethereof a plurality of hollows II andridges I2 which are produced in a manner'to be hereinafter set, forth. The mat contains a high percentage of water which contains the, dyeinsolution or'extremely fine sus-' pension, said dy e being of the bleeding type for the fibrous material employed. While the mat is drying, the bleedingjdye will migrate to the surface thereof and precipitate ina layer I3 (Fig.

' 2), which layer may be partially removed by suitable grinding of the, dry surface so that the resulting product will contain dyed surface portions I3 and undyedportions H 'as indicated in Fig. 3. In "order toproduce this improved fiber mat, arotatably mounted drum or cylinder I5 is provided,the outerperiphery of which is composed t of a foraminous support, such as a wire screen.

This drum dips into a tank I6 which contains a water suspension I! of the bleeding dye such as Pontamine Black E (B. ,C, I. #581) and vegetable fibers such as wood fibers of willow, cottonwood,

' of arms 26, The upper ends of the arms 26 are I the mat and prepare 'it for a subsequent drying operation. v

A roller or other rigid member is rotatably mounted at its ends in the lower ends of a pair pivotally supported on a rod 21 which is received in bearing sockets 28 secured on brackets 29, the latter being supported on the framework of the machine. The arms 26 depend from the rod 21 at an angle to the vertical so that the roller '25 presses lightly against the mat I9 inits formative state due to the action of gravity o'nsaid roller. Springs 30 may connect each of the arms 26 to afixedjsupport to increase the pressure of the roller 25'on themat being formed. However; the

springs 30'rri'ay be dispensed with and themessure of the roll on the mat varied by changing the position ofQthe rod 21 relative to the cylinder I5, thus depending entirely upon gravity. The roller 25 may be located below the level of the fiber suspension II'in tank IE, or it may be raised slightly above the level of saidsuspension with ood results. The actionof the roller 25 is to retard the movement of the loose surface fibers of the mat as the body of the mat moves ahead. When sufiicient loose fibers are built up in back of the'roll, the latter'raises slightly and rides up over the elevated masses of fibers. Suction is maintained on the periphery of the drum I5 so as to insure an integral bond between thefibers in the elevatedareas and the body of the mat. The g ntly in- .clined surfaces IIaof the elevated fiber areas appear on v the leading side of said areas, while the abruptly inclined surfaces I2a appear on the trailing'sides thereof (Figs; 1 and 2). The pressure rollers 24 acting on the belts 22 and 23 serve to flatten down these elevated fiber areas to some extent and give the surface of the mat amore uniform and pleasing appearance.

I In the actual operation of the apparatus thus far described, however, it has been found that some difficulties occur due to the fact that lumpy stock shed by the fiber 'mat in its formative state, particularly'as it passes under the roller25, accumulates at the surface of the water-dye suspension I1 and eventually causes suificient congestion to stop the texturing process accomplished by the roller 25 in its relation to the cylinder I5. Ac-.

cordingly, in order to prevent such difficulties,

there is provided, adjacent the level of the water suspension in the neighborhood of the roller 25,

ing blades, is positively driven at a relatively low speed and serves to mix the lumpy stock shed by a the mat with the body of the water suspension i1 50' as to maintain the stock adjacent the roller 25 in condition to be reformed on the face of the plained. r

bleeding dye migratesto the surface with the water and precipitates as hereinabove described. A high humidity or high moisture content of the air during the initial stages of the drying has been found to promote the bleeding action.

The resulting dry board is then sanded or ground on the uneven surface in order toremove the ridges [2 from the surface and to exposethe undyed or only slightly dyed portions H of the fibrous material.

If desired, the resulting insulating board may be further treated by subjecting it to heat and pressure in a hydraulic press in order to produce what is known as a hard board. The resultant board will alsopresent a variegated surface of the same character as the uncompressed fiber board from which it is produced. The pressing of the hard board may be carried out by any of the well-known processes, the temperatures and pressures employed being largely determined by the characteristics of the desired product.

A dry fiber board produced from a suspension of cottonwood fibers in a dilute solution ($4 of a suitable black dye such as the sodium salt of p sulphobenzene-azo-m-phenylene-diamineazo-diphenyl-azo salicylic acid, and according to the method indicated above, may be pressed in a hydraulic press for about 4 minutes at 1500 to 2000 pounds per square inch and at about 450 F. The bleeding dye imparts a greyish color to portions of the resulting board, and the remaining surface portions are somewhat brown due to the coloration of the fibers during the pressing qperation. The hard board prepared in accordance with this method has a hard, uniformly dense structure with a substantially uniformly porous surface. The product is pleasing in appearance and has improved paintable qualities as previously ex If desired, a dye of a non-bleeding type or an insoluble pigment may also be incorporated intothe original'fibrous suspension. This type of dye will'be retained within the body of the material during drying, and a color may be imparted to portions of the surface of the final product that is different from that of the natural color of the fibers and the bleeding dye. In such a case the area H of Fig. 3 will take on a color imparted by the non-bleeding dye alone, while area I3 will take on a color due in general to the combined effect of the dyes used.

Bleeding dyes that are contemplated for use in this invention are those dyes which are soluble or form fine colloidal suspension in the liquid and are capable of running or bleeding within the material which is being dried. The nonbleeding dyes arethose that become fixed to the material by chemical processes or are prevented from bleeding due to their particle size.

It is not contemplated that this invention be limited to fibrous materials such as may be prepared from vegetable fibers. Any material that may be formed from a liquid suspension of comminuted particles wherein the liquid migrates to the surfaceduring drying or setting of the product may be prepared in a manner as set out in this invention. For example, a variegated surface may be obtained on thesurface of an asbestos-cement shingle if prepared in accordance with this invention, since it is well known that water migrates to the surface and dries off during the setting of these products.

It will also be recognized that it is not necessary to produce a structure having hollows and ridges which may be surfaced by grinding in order to produce a product within the contemplation of thi invention. If desired, an evenly surfaced board or slab may be produced, whose-surfaces may be subsequently scooped out by any suitable means in order to expose the undyed portionsof the material. On the other hand, if a uniform color is desired on the surface of the product, it'

is not necessary that it be surfaced at all. U

While a. particular embodiment of thisinvention is shown above, it will be understood, of course, that the invention is'not to be limited thereto, since many modifications may be made; and it is contemplated, therefore, to cover by the appended claims any such modifications as .fall within the true spirit and scope of this invention.

Iclaim: 1. A method for producing a variegated surface on a porous material which comprises impregnating the material with a liquid solution of a bleeding dye, evaporating the liquid from the surface of the material whereby the dye is concentrated adjacent said surface, and removing a portion of the dyed surface whereby undyedportions are exposed.

2. A method for producing a variegated surface on a porous fiberboard which comprises impregnating the board with a liquid solution of a bleeding dye, evaporating the liquid from the surface of the board whereby the dye is concentrated adjacent said surface, and removing a portion of the dyed surface whereby undyed portions are exposed. I v

3. A method for producing a variegated surface on a material fabricated from a liquid suspension of particles which comprises incorporating a bleeding dye into the suspension, removing a portion of the liquid, shaping the wet material, drying the wet mass whereby the bleeding dye is concentrated .near the surface, and removing a portion of the dyed surface whereby relatively undyed portions are exposed.

4. A method for producing a variegated surface on a fiberboard which comprise preparing a liquid suspension of fibers, introducing a bleeding dye into the suspension, forming a wet mat from said fibers, said mat having at least one irregular surface, drying said mat whereby said dye concentrates near the surfaces of the board, and removing the high portions of the irregular surface of the substantially dry board in order to expose relatively undyed portions.

5.. A method for producing a variegated surface on a fiberboard which comprises forming a mat from a suspension of fibers in a solution of a bleeding dye, wet-pressing said mat whereby excess solution is removed from the mat, drying said mat whereby the dye is caused to concentrate on and'adjacent said surface, and removing a portion ofsaid surface whereby to expose I portions of the core of said board.

'7. A method for producing a two-color variegated surface effect on a fiberboard which comprises forming a mat from a suspension of fibers in a mixed solution of a bleeding dye and a nonbleeding dye, drying said mat whereby the bleed ing dye is caused to concentrate and precipitate principally onand adjacent the surface, the nonbleeding dye remaining substantially equally distributed throughout the mat, and removing a portion of said surface to expose portions of the board free from substantial amounts of the bleeding dye.

8. 'A method for producing a hard, uniformly dense, pressed 'board having a two-color variegated surface which comprises preparing a suspension of vegetable fibers in a mixed solution of a bleeding dye and a non-bleeding dye, forming a, mat from the fiber suspension, producing an uneven surface on at least one side of said mat, drying said mat whereby the bleeding dye is caused to become concentrated principally on and adjacent the surface, the non-bleeding dye remaining substantially evenly distributed throughout the mat, removing the high portions resulting board of the resultinguneven surface of the substantially dry board, and hot pressing the resulting product to produce a board of the density desired.

9. A method for producing a variegated surface on a fiberboard which comprises forming a board impregnated with a liquid solution of a bleeding dye, said board having at least one irregular surface, drying the liquid of the solution from the board whereby the bleeding dye is concentrated mainly on or near the surfaces of said board, and removing the high portions of the irregular surface of the substantially dry board in order to expose the relatively undyed portions.

10. A method of producing a hard, uniformly dense, pressed board having a variegated surface which comprises forming a lightweight board impregnated with a liquid solution of a bleeding dye, said board having at least one irregular surface, drying the liquid of the solution from the board whereby the bleeding dye is concentrated mainly on or near the surfaces of said board, removing the high portions of the irregular surface of the substantially dry board in order to expose the relatively undyed portions, and compressing the to produce the desired dense product. i

HARRY KJLINZELL. 

